Many entities (e.g., companies and other organizations) establish network environments that include two or more separate networks each including numerous computing systems and networking devices. Two or more of the entity's networks may be co-located in a facility, for example in a data center. Instead or in addition, two or more of the entity's networks may each be located in different facilities or data centers at different geographical locations. Often, an entity that implements such a network environment requires high-speed, high-bandwidth, and reliable connectivity between the networks, including those located in different data centers. Often, dedicated physical connections, for example fiber optic connections, are used to provide such connectivity between the separate networks and/or data centers.
A physical connection, e.g. a fiber optic connection, between two networks is not necessarily a single continuous cable connecting the two networks. Instead, such a connection may generally include two or more sections of cable that interconnect between networking devices, for example routers, repeaters, switches, and so on, on the path between the networks. Furthermore, a given physical connection between two networks may follow a physical path that takes the connection through one or more facilities or data centers, through various conduits, along or crossing the paths of other such physical connections, and so on. In other words, the physical network infrastructure of such a network environment is typically complex.
To provide redundancy in such network environments, multiple distinct physical connections (e.g., two or more distinct routes using fiber optic technology) may be designated between two given networks that are co-located in a data center or between two given networks that are located in different data centers, with one route typically designated as the primary route and one or more other routes as alternative routes. If the primary route between two networks goes down, for example as the result of a fiber optic cable being inadvertently cut or of a failure at a networking device on the route, the route's data flow may be redirected onto an alternative route or redistributed onto two or more alternative routes between the two networks.
However, each route (e.g., each fiber optic connection between the two networks) has a capacity limit as to how much total data flow the route can handle. In addition, each of the alternative routes may also be carrying data between two or more networks at some fraction of its capacity on at least a portion of the route. Further, data flow on the routes may vary with time, for example data flow may tend to increase over time on a given route or routes. Due to these and other complexities of the physical network infrastructure in addition to the complexities of network usage and data flow, in such network environments, it has conventionally been difficult to predict network behavior given the many possible failure scenarios and to plan for sufficient redundancy and capacity on the various routes between networks to support a level of reliability that such entities typically require.
While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including, but not limited to.